Thermal Processing of Straw Black Liquor in Fluidized and Spouted Bed (original) (raw)
Related papers
Thermal Degradation of Alkaline Black Liquor from Wheat Straw. 2. Fixed-Bed Reactor Studies
Industrial & Engineering Chemistry Research, 2003
Both pyrolysis and gasification can be considered as alternatives to conventional boilers for recovering chemicals and energy from black liquor. The present work is focused on the study of pyrolysis of alkaline black liquor from straw, and its interest is enhanced by the fact that the material used has hardly been studied before. The influence has been studied of the final pyrolysis temperature (500-900°C), the heating rate (5-30°C/min), and the addition of a determined CO concentration in the N 2 atmosphere (5-40% vol) on both the final solid conversion and the devolatilization rate. The results show that the thermal decomposition of the organic matter fraction of black liquor takes place at temperatures below 550°C in N 2 atmosphere. The weight loss observed at temperatures higher than 550°C is mainly due to reduction reactions of alkaline compounds by the carbon. The final solid conversion and the devolatilization rate are also noticeably influenced by the addition of a certain CO flow rate in N 2 atmosphere.
Basic studies on black-liquor pyrolysis and char gasification
Bioresource Technology, 1993
Pressurized gasification of black liquor is a promising alternative for increasing the electrical-energy production in chemical pulp mills. Design constraints include gasification equilibria and kinetics and constraints imposed by the sodium-sulfur chemistry in the recovery of pulping chemicals.
Journal of Analytical and Applied Pyrolysis, 2001
New alternative processes such as low temperature gasification are currently being developed in order to use of black liquors from pulp and paper mills with energy proposes. The development of these new processes makes necessary to study the behavior of black liquors during pyrolysis and gasification paying special attention on their thermoplastic properties, which can cause important operational problems due to its swelling when heated. Present work is focused to the study of pyrolysis of alkaline black liquors from pulping of straw. The influence of an oxidation stage at low temperature previous to pyrolysis, on specific surface area of the char and on the black liquor swelling, is studied. For that, two main variables are analyzed: time of preoxidation and final temperature of pyrolysis. Dry black liquors from alkaline pulping of straw were used as material. The resulting chars obtained showed a clear decrease in swelling level of the black liquors, as well as an increase on their specific surface area, within the pyrolysis temperature and the preoxidation time. Materials with specific surface areas varying from 2 up to nearly 500 m 2 g − 1 can be produced with the correct choice of experimental conditions. From the results, further research on the influence of a preoxidation stage on black liquors may lead to a better understanding of new alternative processes, which are nowadays being developed.
The pyrolysis behavior of dried and sieved Kraft black liquor particles was examined at high temperatures and heating rates. A CO/H 2 /O 2 /N 2 flame, operating under fuel-rich conditions in a flat-flame reactor, provided a high temperature, oxygen-free post-flame environment. Elemental compositions of the parent black liquor were determined by elemental analysis, and mass release was determined by an ash tracer technique. Effects of temperature and residence time on organic mass loss and primary/secondary tar yields were examined as a function of time and temperature.
Pyrolysis of black liquor solids
Industrial & Engineering Chemistry Process Design and Development, 1986
Black liquor solids of-30+60- ,-60+80-, and-80+150-mesh sire were pyrolyzed in a fixed-bed reactor in an inert atmosphere of nitrogen at 863-1013 K and atmospheric pressure. The effect of reaction time, temperature, and feed particle size on the product yields and the composition of product gases was investigated. The main components of the product gases were hydrogen, methane, carbon monoxide, carbon dioxide, and hydrogen sulfide. A reaction model, in which the black liquor solids decomposed into gas, tar, and char by three parallel first-order reactions, was proposed, and the frequency factors and activation energies of the rate constants were determined.
Pyrolysis of Dried Black Liquor Solids and Characterization of the Bio-Char and Bio-Oil
Materials Today: Proceedings, 2018
Black liquor is a high energy content by-product of paper mill industries which can be processed to generate energy and help in energy sustainability. In this study, experimental analysis were carried out to find various properties of black liquor and characterization of its bio-oil and bio-char obtained through pyrolysis of dried black liquor solids. It was observed from the present study that the temperature has a significant effect on the distribution of products yields. The bio-oil yield was found to be maximum at 500°C temperature with the heating rate of 40°C/min. The bio-oil obtained from Dry black liquor solids (DBLS) has a calorific value of the 29.86 MJ/kg. Chemical composition of the bio-oils was investigated by using FTIR and 1 H NMR analysis. Bio-chars obtained as by-product were also analysed by using SEM-EDX, FTIR and XRD. It was found that the bio char obtained were basic in nature. Hence, it may be used as a potential liming agent for reclamation of acidic soil.
Hybrid Treatment of Black Liquor to Control Scaling in Paper Industry
Pakistan Journal of Engineering and Applied Sciences, 2016
Wood-based raw materials have always been favorable for pulp making purposes. Non-wood raw materials like wheat straw, bagasse, river grass, rice straw, etc. are although abundantly available but globally their use has been discouraged due to presence of silica. Wood is preferable due to absence of silica in it. Silica causes serious problems in the chemical recovery process as it causes scaling of heat transfer surfaces. This phenomenon reduces the plant production capacity and causes black liquor wastage, which is environmentally and economically undesirable. Black liquor is the byproduct obtained from cooking process at the pulp washing stage. The best way to treat black liquor is to process it through chemical recovery plant where it is first evaporated and then burned. In this research article, a number of experiments were carried out by using different conditions of temperature and residence time. Encouraging results were obtained and compared with other available techniques.
Thermodynamic Analysis of Black Liquor Steam Gasification
BioResources, 2011
Pulp and paper mills represent a major platform for the use of abundant, renewable forest-based biomass as raw material. The pulping processes produce a large amount of black liquor solids, which is currently burnt in a conventional Tomlinson recovery boiler for recovery of energy and inorganic chemicals. This combustion technology can recover chemicals with good efficiency, and steam and power can be produced for the mills. However, Black Liquor Gasification (BLG) can be used to substitute for the combustion process for potential higher energy efficiency, lower greenhouse gas emissions, and more safety. With BLG technology, current pulp and paper mills can be extended into future biorefineries. In this work, a thermodynamic equilibrium model using Gibbs free energy minimization approach and the software FactSage are utilized to analyze the thermodynamic equilibrium constraints of the complex multiple phase reactions and the effects of different operating conditions during black liquor gasification. The modeling results can help better understand the black liquor gasification process and be useful in process modeling and analysis of the future BLG-based biorefinery.
Influence of char formation conditions on pressurized black liquor gasification rates
Carbon, 1998
Black liquor is a by-product which results from the pulping of wood in a solution of NaOH and Na 2 S, and accounts for a significant fraction of the total energy production in papermaking countries. Conventionally, the liquor is concentrated and burned in large recovery boilers, but pressurized gasification of black liquor is a promising alternative. A key concern for pressurized gasification is how char formation conditions affect its resulting reactivity. We studied this and found that prolonged exposure to high temperatures decreases the reactivity by two mechanisms, thermal annealing and, in the presence of CO, deposition of solid carbon. Increased pressure during char formation also resulted in lower gasification rates, with chars formed at 20 bar displaying reactivities less than half that of chars formed at atmospheric pressure. The results also suggest that kinetic behavior observed in previous studies of pressurized black liquor gasification has mistakenly been attributed to reaction kinetics alone, while in fact the char formation technique has influenced its reactivity.
New treatment of the black liquor produced from pulping of rice straw
Black liquor the main waste remained from paper industry composed mainly of some organic compounds as a soluble salts and a high portion of sodium silicate. The idea of this paper is to transfer the inorganic part from this waste into useful product (calcium silicate hydrate) which has a lot of known applications nowadays. The preparation of calcium silicate from black liquor was done through direct reaction between the black liquor, calcium carbonate and calcium hydroxide and boiling for about 2 hrs. This method was known as hydrothermal method. The obtained materials as well as the raw materials were investigated using both IR and XRD analyses.